Above the oil: A view of Alberta's oil sands

The controversial Keystone XL pipeline is back in the news, with the Republican-controlled House voting last week to approve the project. The legislation, however, was narrowly rejected by the Senate.

The pipeline, which would create an oil transport system from Canada to the Gulf of Mexico, is expected to come up again when the new Congress convenes next year, reigniting a political battle for Obama, who has hinted in the past that he would veto such legislation.

At the heart of the project could be Canada’s Alberta oil sands – the third-largest crude oil reserve in the world, next to Saudi Arabia and Venezuela. The pipeline would potentially move hundreds of thousands of barrels of crude a day from the Alberta tar sands through the U.S. and to the Gulf.

Proponents of Keystone — mainly labor unions, oil companies, Republicans and moderate Democrats— argue the plan would create thousands of jobs and make the country less dependent on oil from the Middle East. Critics say the project would release dangerous greenhouse gas emissions, would not bring in significant numbers of new jobs, and would have no effect on U.S. gas prices.

The biggest issue with the tar sands (a combination of sand, water clay and heavy crude oil) is just how it is extracted from the ground. Currently, two methods, which environmental groups have heavily criticized, are being used. One involves steam extraction to separate the oil, but as a result causes toxic waste runoff. Another method involves open-pit mining but results in forests being completely cleared, making room for heavy machinery.

Alberta’s oil sand production is expected to increase from approximately 2 million barrels a day to 3.8 million barrels a day by 2022.